1. Field of Invention
Apparatuses and methods consistent with the present invention relate to signal processing, and more particularly, to signal processing and coring to reduce noise included in a video signal.
2. Description of Related Art
In general, a signal processing apparatus such as a television, a set top box or the like includes a decoder, a scaler, an Integrated Circuit (IC) for image quality improvement, etc. The signal processing apparatus processes and outputs a video signal received from an external device such as a computer, a digital versatile disc (DVD) or the like or a broadcasting signal received from a broadcasting station.
The signal may include noise while being transmitted or received, which may cause an error in the signal processing. Particularly, in the case of a video signal having a high frequency, the noise becomes distinguished in an image thereof.
In a related art signal processing apparatus, a coring method has been typically employed to reduce noise.
FIG. 1 illustrates such a related art signal processing apparatus. As shown, the signal processing apparatus includes a high pass filter (HPF) 11, a first mixer 12, a coring unit 13, and a second mixer 14.
Only a high frequency component of an input video signal passes through the HPF 11, and then, is cored by the coring unit 13 for noise removal. The high frequency component which passes through the HPF 11 is removed from the video signal by the first mixer 12. The high frequency component cored through the coring unit 13 and a low frequency component output from the first mixer 12 are mixed with each other by the second mixer 14 into a video signal with reduced noise.
As shown in FIG. 2, the coring unit 13 changes a component of the high frequency signal passed through the HPF 11, having a level within a predetermined reference range −a to a, to zero, thereby removing it from the output. Generally, a signal component having a low level which causes noise is removed during this process. The reference range is pre-set in a manufacturing process of the signal processing apparatus.
In the case of a weak electric field signal which is weak in transmission of the signal and has a low signal-to-noise ratio, noise is relatively distinguished in an image thereof compared with a signal having a high signal-to-noise ratio, even with the same noise included. Thus, in order to reduce noise in the weak electric field signal, the reference range of the coring unit must be extended.
In the related art signal processing apparatus, the reference range of the coring unit which has been pre-set in the manufacturing process of the signal processing apparatus is fixed and cannot be changed later. Thus, if the reference range is extended, details of an image become deteriorated in the case of a high signal-to-noise ratio of an input video signal.